Tiny Crystals in Mars Rocks Finally Reveal What Happened to Water on the Red Planet

Despite the superstar status of scientists like Albert Einstein (who upended Newtonian physics from a Swiss patent office) and Richard Feynman (who liked to play Russian Roulette with a sphere of nuclear material called the "demon core"), most scientific breakthroughs are built on small, obscure discoveries and the scientists who recognize that this composition of gas or this piece of bone changes everything. We may have that sort of situation on our hands over at NASA right now, thanks to some very small marks left in Martian rocks, which were spotted by the Curiosity rover.

If you're not up-to-date on Curiosity, it's currently trundling around Vera Rubin Ridge, where it managed to take a breathtaking panorama shot of its travels so far.

Now Curiosity has found some small marks in the bedrock of the ridge that may give insight into exactly when water on Mars started to disappear.

The marks were apparently caused by gypsum crystals, which have since disappeared, but the distinctive shapes of those crystals have been left behind. This has allowed scientists to hypothesize that the crystals formed in steadily evaporating water, which became saltier over time. These crystals aren't the first evidence of lakes in Gale Crater, the giant impact crater Curiosity has been exploring since it landed, but they do offer an answer to the question of when and how those lakes disappeared.

According to Project Scientist Ashwin Vasavada at NASA:

"So far on this mission, most of the evidence we've seen about ancient lakes in Gale Crater has been for relatively fresh, non-salty water. If we start seeing lakes becoming saltier with time, that would help us understand how the environment changed in Gale Crater, and it's consistent with an overall pattern that water on Mars became more scarce over time."

Either way, if these crystal marks do indeed come from evaporating lakes (or even from underground rocks infused with water), Vasavada says it would mean that Mars used to be a stable, habitable place. Whether or not life developed on the Red Planet, it bodes well for the next generation of terraformers looking to turn Mars into a human paradise.